Protective cap

ABSTRACT

The invention relates to a protective cap for a lens or ocular end of an optical device, such as an observation device, with an end wall and with a tubular cap casing extend around at least certain regions of the end wall. The end wall comprises at a first layer in at least certain regions and an insert part made separately from it, and the material of the first layer or insert part has a higher modulus of elasticity than the material of the cap casing.

BACKGROUND OF THE INVENTION

The invention relates to a protective cap for a device, in particular a lens or ocular end of an optical device, such as an observation device, as described in claim 1.

Document DE 939 192 C discloses a protective cover made from a transparent material for lenses and oculars of optical devices, in particular photographic lenses. In this instance, a part of the protective cover is made from a transparent material so that it has a magnifying effect. As a result, a magnifying glass is always available for obtaining a magnified view, making it easier to determine the values which need to be set for the lens or ocular. A protective cover which can be used as a magnifying glass offers a major advantage for persons with impaired sight because the numbers provided on the lens, closure and aperture ring are usually very small and are difficult to make out without visual aids. The entire protective cover is made from one material, and may additionally be provided with a velvet tape in the region where the protective cover is fitted on the lens.

Document DE 1 761 392 U discloses protective covers for lenses of field glasses, and the covers are individually attached to the bottom ends of the carrying strap of the field glasses. The covers can therefore be individually fitted on the lens barrels of the field glasses and are held on the barrels by static friction. The ends of the carrying strap are usually threaded through eyes attached to the field glasses and the strap then pulls the covers up to the eyes once they have been removed. They therefore lie firmly against the field glass housing and no longer prevent use of the field glass.

BRIEF SUMMARY OF THE INVENTION

The underlying objective of this invention is to propose a protective cap for a lens or ocular and an optical device, in particular an observation device, which facilitates and therefore improves handling when fitting the protective cap on the optical device.

This objective is achieved by the invention on the basis of the characterizing features defined in claim 1.

The surprising advantage gained as a result of the characterizing features defined in claim 1 resides in the fact that the end wall and cap casing of the protective cap are made from materials which have a different bending stiffness or bending strength from one another or a different hardness, and the respective properties of the individual components can therefore be specifically adapted to suit the particular intended purpose. A sufficient protective and damping effect can be obtained for the optical device as a result, especially in the external peripheral region of the protective cap, whilst nevertheless stiffening or reinforcing the end wall for the fitting or snap-fitting operation of the protective cap. As a result, the protective cap as a whole can firstly be fitted in a pre-centered position on the ocular and/or lens of the optical device, after which a light pressure merely has to be applied centrally to the end wall, in particular at its center, so that the entire protective cap is fully fitted or pushed onto the lens or ocular to be protected in the region of the end wall by means of this pressing force. In the case of protective caps which are of a very soft and elastic design, this centrally positioned fitting movement is not possible. In the past, it ha been necessary to apply pressure distributed around the external circumferential edge of the protective cap in order to be able to fit or snap-fit it correctly. Due to the stiffer or more bending resistant material used for the end wall, the fitting operation can now take place using one finger.

Also of advantage is another embodiment defined in claim 2, where at least the end wall of the protective cap can be inserted in a sort of sandwich component made from materials with a differing modulus of elasticity, which on the one hand enables the stiffness of the protective cap in the region of the end wall to be specifically pre-defined, whilst on the other hand nevertheless imparting an adequate protective and damping effect to the entire protective cap for the optical device. Due to the multi-layered design, the material used for the snap-fitting operation on the optical device and hence the one with the lower modulus of elasticity than the other layer is reinforced to the degree that the entire protective cap can firstly be placed on the ocular and/or lens in a pre-centered position, after which another central pressing force merely has to be applied to enable the protective cap to be fully fitted or pushed on in the region of the end wall by means of this pressing force.

Another possible embodiment is defined in claim 3, whereby a component can be produced in a manufacturing process during which the insert part or first layer can be embedded or on-molded. Furthermore, however, the protective cap can still be easily adapted to suit different intended purposes.

As a result of the embodiment defined in claim 4, in addition to centering the cap casing internally by means of the circumference of the ocular or lens end, an additional hold for the entire protective cap can be provided on its external face. As a result, the end of the optical device to be protected can be covered around its entire circumference and is therefore optimally protected.

As a result of another embodiment defined in claim 5 or 6, an even better hold of the protective cap is obtained in the protective position fitted on the optical device. In addition however, the seal of the optics of the optical device can be improved, thereby preventing dust and dirt from getting to the optical components during storage or transportation.

Also of advantage is another embodiment defined in claim 7 because the process of fitting and removing the protective cap on or from the optical device can also be made easier, and air is able to flow in and out at predefined points. During fitting, this enables any air which might otherwise be trapped between the protective cap, barrel and lens to escape so that no air cushion is created which might push the protective cap off.

The advantage of the embodiment defined in claim 8 is that it also makes the process of removing the protective cap easier because if the leg of the retaining shoulder is sitting firmly and tightly, air is already able to flow as far as the cap casing from outside. The fitting operation is also made easier because any quantity of air contained in the housing compartment for the ocular can also easily escape from it. This further improves the hold of the protective cap on the optical device.

Also of advantage is another embodiment defined in claim 9 because by opting for the high modulus of elasticity, the degree of stiffness or reinforcement can be fixed for the entire end wall, which means that the degree of flexing which occurs during the fitting movement can be significantly reduced compared with conventional protective caps.

As a result of the embodiment defined in claim 10, the stiffness or flexibility of the end wall can easily be adapted to suit different conditions of use.

In the case of another embodiment defined in claim 11, it is possible to manufacture the layers separately. Accordingly, the first layer or insert part is made first of all in a separate manufacturing process and is joined to the material of the other layer or cap casing during another forming process used to produce to it, for example molded to or embedded in it.

Also of advantage is another embodiment defined in claim because the choice of mutual materials enables a perfectly bonded connection to be obtained between the components to be joined.

The advantage of the embodiment defined in claim 13 is that not only is it possible to make the end wall stiffer, the cap casing can also be made stiffer.

In the case of another embodiment defined in claim 14, a minimal deformation distance of the end wall in the radial direction is achieved in the pre-tensioned retaining state on the optical device to be protected on the one hand, in addition to which there is no need for excessive deformation of the whole of the end wall during the fitting movement. This minimizes fitting force and also increases the retaining force in the fitted state.

Another embodiment is defined in claim 15, whereby it is possible to opt for a slimmer wall thickness for the insert part but a bending-resistant or stiff design of the end wall can nevertheless be achieved.

Also of advantage is an embodiment defined in claim 16 because force can be transmitted more rapidly in co-operation with the shoulder in the cap casing during the movement of pushing on the protective cap and the deformation distance of the end wall can also be kept short.

The advantage of an embodiment as defined in claim 17 is that an additional mechanical connection is obtained between the two layers disposed one on top of the other.

In this respect, an embodiment as defined in claim 18 has proved to be of advantage because the stiffer and more solid material needed for the pushing-on movement is already disposed on the external face of the protective cap and it can therefore be protected against high mechanical abrasion in the region of the end wall. Furthermore, the user has an easy way of telling that an appropriate pressing force must be applied to the protective cap in the region of its center in order to fit it the optical device to be protected.

Based on an advantageous embodiment defined in claim 19, an additional mechanical, positive connection is obtained between the layers to be joined to one another.

Also of advantage is an embodiment defined in claim 20, because additional mechanical support is provided not only in the peripheral region, but also in the region of the center where there is the biggest relative mutual shifting between the layers, thereby enabling the overall strength to be increased.

As defined in claim 21, additional stiffening of the protective cap can also be achieved beyond the region of the end wall, which makes it even easier to fit the protective cap on the optical device to be protected.

In the case of the embodiment defined in claim 22, a predefined weaker region is obtained for the retaining shoulder extending out from the ocular or lens end, thereby making the snap-fitting operation significantly easier.

Another possible embodiment is defined in claim 23 whereby a part can be obtained from a manufacturing process where the insert part for the first layer can be embedded or on-molded. In addition, however, the protective cap can also be easily adapted to different conditions of usage.

Finally, another embodiment defined in claim 24 is of advantage because an adequate damping effect can be obtained in the peripheral region of the protective cap for the optical device to be protected. Moreover, due to the higher elastic deformability, a sufficient friction fit can be obtained to hold the protective cap on the optical device to be protected.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a clearer understanding, the invention will be explained in more detail below with reference to the appended drawings.

FIG. 1 is a simplified schematic diagram illustrating a first embodiment of a protective cap proposed by the invention;

FIG. 2 shows a view of the protective cap illustrated in FIG. 1 from underneath;

FIG. 3 is a view of the protective cap illustrated in FIGS. 1 and 2 in section along line III-III indicated in FIG. 2;

FIG. 4 is a diagram in section and on a larger scale illustrating a partial section of the external peripheral region of the protective cap illustrated in FIGS. 1 to 3;

FIG. 5 is a diagram in section and on a larger scale illustrating a partial section of another possible embodiment of the protective cap;

FIG. 6 is a simplified schematic diagram showing a view in section of another embodiment of the protective cap;

FIG. 7 is a simplified schematic diagram showing a view from underneath of another embodiment of the protective cap;

FIG. 8 is a simplified schematic diagram showing another embodiment of the protective cap viewed in section along line VIII-VIII indicated in FIG. 9;

FIG. 9 is a view from underneath in the direction of arrow IX indicated in FIG. 8 showing the protective cap illustrated in FIG. 8;

FIG. 10 is a simplified schematic diagram showing another embodiment of the protective cap viewed in section.

DETAILED DESCRIPTION

Firstly, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc., relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described. Individual features or combinations of features from the different embodiments illustrated and described may be construed as independent inventive solutions or solutions proposed by the invention in their own right.

All the figures relating to ranges of values in the description should be construed as meaning that they include any and all part-ranges, in which case, for example, the range of 1 to 10 should be understood as including all part-ranges starting from the lower limit of 1 to the upper limit of 10, i.e. all part-ranges starting with a lower limit of 1 or more and ending with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

FIGS. 1 to 4 illustrate a first possible embodiment of a protective cap 1 for an optical device 2, such as an observation device, which may be construed as an independent solution in its own right, and only a partial section of the optical device 2 is illustrated on a simplified basis in FIG. 3, indicated by broken lines.

The optical device 2 has a lens end and/or ocular end, although this is not illustrated, and a protective cap 1 may serve as a cover for both the lens end and the ocular end. Accordingly, the size of the protective cap 1 is adapted to suit the specific dimensions of the optical device 2. The optical device 2 may be a monocular or binocular telescope or field glass magnifier. However, it might also be a lens of a camera or such like, which is covered by the protective cap 1.

The protective cap 1 has an end wall 3, which closes off the lens or ocular end of the optical device 2 to be covered from the outside. Disposed or arranged on the external circumference of the end wall 3 is a cap casing 4. In the embodiment illustrated as an example here, the cap casing 4 is provided as a means of inserting inside the barrel of the lens and/or ocular end. To provide a better hold on the optical device 2 and cover the optical device 2, it is of advantage if an L-shaped retaining shoulder 5, as viewed in axial section, is provided or disposed on the cap casing 4. The L-shaped retaining shoulder 5 in turn has legs 6, 7. The first leg 6 is joined to the end wall 3 or to the cap casing 4 and extends radially out from it. The leg 6 is preferably also disposed at an angle to the cap casing 4, and might also be said to be disposed in an approximately flat or parallel arrangement with respect to the end wall 3. The other leg 7 extends approximately parallel with the cap casing 4 but is disposed radially at a distance outside of it. Since both the cap casing 4 and the other leg 7 are of an approximately tubular shape, they can be described as having an approximately cylindrical shape and a longitudinal axis extends between the two end regions of the cap casing 4 or legs 7.

The two legs 6, 7 of the retaining shoulder 5 in co-operation with the cap casing 4 bound a preferably circumferentially extending tubular or cylindrical shaped housing compartment 8. This housing compartment 8 is used to accommodate the complementary part of the optical device 2 so that it can be releasably retained on it. Due to the material chosen for the cap casing 4 and the legs 6, 7 of the retaining shoulder 5, a sufficient adherence or retaining effect can be obtained when the protective cap 1 is disposed in the protective or covering position on the optical device 2 due to the elastic deformation of these components.

Known optical devices 2 usually have a circular cross-section in the region of their lens or ocular end, and the protective cap 1, in particular the cap casing 4, is adapted to this and is likewise round or circular and, in the case of the cap casing 4, also of a tubular shape. The end wall 3 has a center 9, from which the cap casing 4 is radially spaced apart.

In the embodiment illustrated as an example here, the end wall 3 is preferably of a multi-layered design from its center 9 as far as the cap casing 4, and the material of a first layer 10 has a higher modulus of elasticity and/or a higher Shore hardness A than the material of another or second layer 11. In this respect, however, the first layer 10 may form only certain regions or certain portions of the end wall 3.

Such protective covers are usually made from a rubber-like or silicone-type material with a high damping capacity so as to be able to provide sufficient damping in the event of impacts to the optical device 2 on the one hand and on the other hand so as to sit sufficiently tightly on the optical device 2 due to an easy ability to deform elastically, usually by a friction fit, to perform the protective function.

Accordingly, it is of advantage to opt for a modulus of elasticity for the first layer 10 with a lower limit of 2000 MPa, in particular 5000 MPa, and an upper limit of 210000 MPa, in particular 15000 MPa. A preferred value in this respect may be between 6000 MPa and 8000 MPA, for example 7000 MPa. The test method used is that defined by standard ISO 527-1/-2 and the test temperature is 23° C.

The modulus of elasticity of the second layer 11 is selected so that it is lower than the modulus of elasticity of the first layer 10. The Shore hardness A of the second layer 11 may be selected with a lower limit of 50 and an upper limit of 80.

The first layer 10 which is harder or more solid and hence stiffer than the second layer 11 may be made from a material selected from the group comprising plastic, metal, metal alloys, word or a timber-like material, glass, ceramic, composite components. The plastic might be, for example, the material PBT-GF20 (polybutylene terephthalate) sold by the BASF company under the trade name “Ultradur®—B 4300 G4 High Speed”. Using this material, to which up to 20% glass fibers are added, enables stiff, tough and dimensionally stable parts to be manufactured. Where possible, various fibers or yarns could be embedded in any of the materials listed above.

If glass or an appropriate transparent plastic is used, the first layer 10 may also serve as a filter element for observing the sun, for example, or as a selective laser protective filter where it is necessary to influence transmission behavior. This means that the protective cap 1 can fulfill a dual function, in which case it will not be necessary to remove it from the device 2, in particular the observation device, for one specific intended application. Choosing the color of the material of the layer 10 accordingly will open up a range of different applications.

When choosing the material for the layer 10, however, care must also be taken to ensure that it is compatible with the material chosen for the device 2 to be protected, for example in order to prevent corrosion etc., between components that are in contact with one another.

The advantage of using a multi-layered design for at least the end wall 3 is that it enables several different materials to be used in combination with one another, making it easier and simpler to adapt the strength properties of the entire protective cap 1 starting from its center 9 as far as the cap casing 4 to suit different applications. For example, it is possible to design the first layer 10 as a separate flat insert part 12, in which case it is surrounded by the second layer 11 in at least certain regions and in particular is embedded in certain regions of the second layer 11.

In this respect, the insert part 12 may be produced as a separate component in a separate injection casting process and then joined to the other material of the second or other layer 11, for example molded onto it, during the process of manufacturing the protective cap 1 as a whole. This being the case, it may be said that the material of the second layer 11 or cap casing 4 is injected onto the material of the first layer 10 or insert part 12. Alternatively, however, it would also be possible for the second layer 11 or the insert part 12 made from it to be molded onto the material of the first layer 10 as it is being produced. Based on an expedient choice of materials for the first and second layer 10, 11, a positively adhered join can be produced in the region of the mutual contact surfaces. Another alternative option, however, would be to introduce the material used to form the first layer 10 and the material used to form the second or other layer 11 into the injection casting mold for a so-called two-component injection casting process, either one after the other and/or together, and thus form the insert part 12 or first layer 10 followed by the other layer 11. It would also be possible to reverse the production sequence.

The insert part 12 or layer 10 could also be made from braids, knitted materials, fleece and non-woven materials selected from different materials or combinations of materials. If chosen accordingly, it would also be possible to obtain sufficient stiffening, in particular bending resistance, in the end wall 3, and the entire insert part 12 can then also be embedded in the second layer 11. Due to the individual yarns or a lattice pattern, the material used to produce the second layer 11 will be able to pass through and thus establish a positive bond between the two layers 10, 11.

The first layer 10 or insert part 12 made from it extends out from the center 9 in the direction towards the cap casing 4. It may also be only a partial region as viewed in the radial direction if the lens or ocular end of the optical device 2 is of a circular design, e.g. ⅓ to ⅔ of the distance between the center 9 and cap casing 4, or alternatively may extend continuously as far as the cap casing 4 but optionally also beyond it.

It is also of advantage if the insert part 12 also incorporates or has a tubular shoulder 13 and the shoulder 13 is embedded or accommodated in the cap casing 4. This shoulder 13 is disposed on what is usually a disc-shaped insert part 12 in the region of its external circumference, and the insert part 12 formed in this manner is likewise of a cap-shaped design overall. However, the shoulder 13 may be disposed or provided on only certain regions in the circumferential or peripheral region of the insert part 12.

As may best be seen from FIG. 3, the insert part 12 is of a crown-shaped design as viewed in axial section, starting from its external circumference through to its center 9 on the side facing the optical device 2 to be covered—in other words the side facing the cap casing 4. Due to the preferably circular design of the insert part 12, it may be described as bowl-shaped or spherical. As viewed in axial section, the insert part 12 therefore has an arcuate curvature and the camber is directed towards the side of the cap casing 4. On the side facing the second layer 10, the insert part 12 has a convex curvature as viewed in axial section.

As may also be seen from FIG. 3, the insert part 12 is disposed in the region of the end wall 3 on the side facing the protective cap 1 covering the optical device 2. The disc-shaped insert part 12 therefore forms an internal surface 14 of the protective cap 1 in the region of the end wall 3, which extends continuously as far as the cap casing 4 preferably extending all the way round.

To improve the hold or molding of the other or second layer 11 on the first layer 10 or insert part 12, an orifice may be provided in at least the center 9 of the insert part 12, through which the material or the material of the second layer 11 extends. Depending on the shape of the orifice 15, another positively fitting hold can be obtained between the two layers 10, 11 in the region of the end wall 3. This is of advantage if the material of the first layer 10 is such that it can not be permanently bonded to the second layer 11, for example fused or welded to it.

The first layer 10 of the end wall 3 is predominantly formed by the insert part 12 in this instance, which is made from one of the materials listed above or any combination of them. The second layer 11 of the end wall 3, cap casing 4 and optionally the retaining shoulder 5 incorporating the two legs 6, 7 preferably constitute a single cohesive component, which may be termed as a main body 16. The material used to make the above-mentioned individual parts of the main body 16 may be selected from the group comprising elastomeric materials such as silicone (synthetic polymers) in particular silicone 70 Shore A or silicone caoutchouc or silicone rubber, rubber such as natural rubber or synthetic rubber, in particular nitrile rubber (NBR) or styrene-butadiene rubber (SBR), thermoplastic elastomers (TPE). The above-mentioned materials used to make the main body 16 should therefore be flexible and elastically deformable and optionally should also be such that they elastically rebound automatically. In this respect, plastics which have such properties have also proved to be of particular practical advantage.

In order for the protective cap 1 to continue to be held on the optical device 2 once it has been removed from the protective position on it so that it is not a loose part held in the hand, it is of advantage if the protective cap 1 is provided with an additional, integrally connected fixing element 18 via an elastic connecting element 17. If the main body 16 described above is produced jointly with the connecting element 17 and fixing element 18 in a single manufacturing process, the same material may also be selected for all of them.

The fixing element 18 is an annular or tubular component, which is also adapted to what is usually a round contour of the barrels. If the barrels are of a different shape, the cross-sectional shape of the fixing element 18 may also be adapted to it in order to ensure correct orientation on the optical device 2. By preference, however, a round design is selected because if the fixing element 18 is sufficiently elastic, it can also be adapted to the cross-sectional shape of the barrels. The broken lines shown in FIG. 3 illustrate the position of the fixing element 18 when fitted on the optical device 2.

In order to make handling of the push-on and removable protective cap 1 easier, it may have an additional grip 19 on its external circumference. The advantage of the multi-layered, in particular two-layered, design of the end wall 3 is that the main body 16, in particular the second layer 11, of the cap casing 4 and retaining shoulder 5 can be made from a relatively soft and elastic material, thereby imparting adherence and impact damping properties to the part of the optical device 2 to be protected. The additional first layer 10 or the insert part 12 made from it imparts extra stiffness to the end wall 3, so that when a pressing force is applied to the protective cap 1 when fitting it on the barrel, the end wall 3 is not excessively deformed and the protective cap 1 can be fitted or snap-fitted on the optical device 2 with one hand or one finger. The stiffness of the end wall 3 is increased to the degree that the cap casing 4 can also be disposed lying inside on the barrel to be protected in the protective layer. Since the longitudinal extension or axial extension of the cap casing 4 is longer than the leg 7 in the same direction, there is an initial centering effect on the internal face of the barrel and the annular or tubular barrel is not pushed into the housing compartment 8 until after a certain pushing-in distance.

As may also be seen by comparing FIGS. 1 and 2, the protective cap 1 is provided with at least one cut-out 26 on the side of the cap casing 4 facing away from the center 9—in other words on its external face 28—in order to make it easier to fit it on or remove it from the optical device 2, which preferably extends as far as the leg 6 of the retaining shoulder 5. This cut-out 26 is preferably disposed in the region of the grip 19 and may be based on a design distributed around the circumference. The purpose of the cut-out 26 is to vent and/or air the cavity bounded by the barrel and protective cap 1. As a result, any air which might be present in this cavity can largely escape through the cut-out 26 when fitting the protective cap 1. The same applies when removing the protective cap 1 because air is able to flow into the cavity through the cut-out 26, thereby preventing a vacuum from being created during removal, which would otherwise produce an additional suction or adhering effect.

If the retaining shoulder 5 sits with its leg 7 in a tight or sealing abutment on the external face of the barrel of the optical device 2 when the protective cap 1 is in the fitted position, at least one other cut-out 27 may also be provided on the side of the leg 7 facing the cap casing 4 or center 9—in other words on the internal face. This cut-out 27 also extends in the axial direction from a terminal end face of the leg 7, preferably continuously, as far as the first leg 6 of the retaining shoulder 5. This being the case, most of the air which might be present in the housing compartment 8 is also able to escape through the cut-out 27. The two cut-outs 26, 27 are preferably disposed opposite one another as viewed in the radial direction. The cut-outs 26, 27 may also be described as ridges or channels.

In order to fix a predefined portion where the cap casing sits in contact with the barrel of the optical device 2, at least one projection 29 may be provided on the cap casing 4 on the side facing away from the center 9—in other words on its external face 28. The projection 29 illustrated here has a cross-section, as viewed in axial section, which more or less corresponds to an arc and extends radially out from the external face 28 of the cap casing 4. The projection 29 may be provided in certain regions only or alternatively may extend continuously around the circumference. Depending on the cross-sectional shape selected as well as the number and disposition of the projection or projections 29 on the cap casing 4, the centering effect and/or the retaining force of the protective cap 1 in the position fitted on the optical device 2 can be selected and varied accordingly. It is also of advantage if the projection or projections 29 are spaced back from an end face 30 of the cap casing 4 in the direction towards the end wall 3, and the end face 30 is disposed on the side of the cap casing 4 facing away from the end wall 3. Accordingly, the external face 28 through to the projection 29 may serve as an additional centering aid or guide for the protective cap 1 when fitting it on the barrel of the optical device 2. The continuous projection 29 may then be interrupted in the region of the cut-out 26 described above.

Due to the additional stiffness imparted to the end wall 3 by the insert part 12, handling may be effected in the region of the center 9 so that force can be transmitted or introduced into the cap casing 4 without the end wall 3 being subjected to excessive deformation if a relatively soft material is selected for the layer 11 or main body 16. If only a single material were used but one which had sufficient flexibility or elasticity for the retaining or adhering operation, the end wall 3 would permit high deformation when force is applied to the center 9 and thus make the snap-fitting operation much more difficult or even prevent the fitting operation proposed by the invention altogether. This would make it necessary to hold the whole protective cap 1 by its external circumference and then fit it on the optical device 2.

FIG. 5 illustrates another embodiment of the protective cap 1 which may also be regarded as a solution in its own right, the same reference numbers and component names being used for parts which are the same as those in the description given with respect to FIGS. 1 to 4 above. To avoid unnecessary repetition, reference may be made to the detailed description given in connection with FIGS. 1 to 4 above.

This protective cap 1 is also of a multi-layered design in the region of its end wall 3 and comprises the first layer 10, the second layer 11 which is preferably joined to it, the cap casing 4 and optionally the L-shaped retaining shoulder 5 with its legs 6, 7.

By contrast with the embodiment of the protective cap 1 described above, the insert part 12 formed by the first layer 10 is disposed in the region of the end wall 3 on the side facing away from the optical device 2 to be covered in this instance. Accordingly, when the protective cap 1 is in the position fitted on the optical device 2 to be covered or protected, the insert part 12 or first layer 10 constitutes at least a major part of the external surface of the end wall 3. To improve the adherence or connection of the first layer 10 to the material of the second layer 11, it is of advantage if at least one projection 20 is provided on the insert part 12, which projects or extends into the material or the material of the second layer 11. By preference, the projection 20 is disposed at the center 9 of the insert part 12. It would also be possible to provide several of the projections 20 distributed on the insert part 12 in order to establish a positive adherence or connection to the material of the second layer 11 or main body 16.

In the region of its external circumference, the insert part 12 again has the preferably tubular shoulder 13 extending into the cap casing 4. This also imparts additional stiffness to the cap casing 4, thereby enabling a better guiding action to be obtained by the cap casing 4 during the fitting movement.

The preferably flat insert part 12 may also have a flange extending radially out from the tubular shoulder 13 on its external circumference, which preferably extends on the external surface into the L-shaped retaining shoulder 5. In this region, a flat arrangement may be provided between the external surface of the insert part 12 and the L-shaped retaining shoulder 5.

Irrespective of the above, however, it would also be possible to provide an arrangement whereby an end face 22 of the flange 22 made from the material or the material of the second layer 11 facing away from the center 9 of the insert part 12 extends in the direction towards the center 9, thereby ensuring that the insert part 12 is completely embedded in its external circumferential region.

The material of the second layer 11 in the region of the end face 22 of the flange 21 facing away from the center 9 may also be spaced at a distance apart therefrom. A minimal gap 23 is therefore left free between the end face 22 and the material of the retaining shoulder 5 of the main body 16. This results in a simple and easy deformation movement of the retaining shoulder 5 in order to vary the housing compartment 8 for the snap-fit operation.

If the flange 21 is not provided, an end face 24 of the insert part 12 may likewise be disposed radially at a distance apart from the material of the second layer 11 so that a gap 23 is also formed. This again means that the insert part 12 may extend circumferentially and thus be fully embedded at its external circumferential region.

Irrespective of the above, however, it would also be possible for the end wall 3 to be of a three-layered design in at least certain regions, in which case it may be made from the same material as that used for the main body 16. Another option would be to use a different material. This additional layer 25 is indicated by broken lines in FIG. 5. It would therefore be possible to embed the first layer 10 or insert part 12 completely in the main body 16. It would also be conceivable to opt for this variant in the case of the embodiment described with reference to FIGS. 1 to 4.

A gap width of the gap 23 may be formed between closely lying but not integrally formed parts and thus have a distance of from 0.0 mm up to a few tenths of a mm or bigger.

FIG. 6 illustrates another embodiment of the protective cap 1, which may also be construed as an independent embodiment, the same reference numbers and component names being used to denote parts that are the same as those described in connection with FIGS. 1 to 5 above. To avoid unnecessary repetition, reference may be made to the detailed description of FIGS. 1 to 5 above.

The protective cap 1 illustrated here has only the first layer 10 in the region of its end wall 3, which in the embodiment illustrated as an example is the insert part 12. In its circumferential region, it extends into the cap casing 4 and is preferably surrounded by the latter around its entire circumference. Accordingly, the end wall 3 is based on a design of only one layer and the material used to make the layer 10 is a more solid and stiffer material than that of the cap casing 4.

To transmit force more effectively from the insert part to the cap casing 4, the preferably circumferentially extending shoulder 13 may also be provided on the insert part 12.

The cap casing 4 is again used for inserting in the internal face of a barrel of the optical device 2, not illustrated. In addition to the cap casing 4, the retaining shoulder 5 with its legs 6, 7, which is also L-shaped as viewed in axial section, may also be provided as described above. To make handling of the protective cap 1 easier, both the grip 19 and the cut-outs 26, 27 described above may be provided. The same also applies to the projection 28, which usually extends around the circumference. In order to hold the protective cap 1 on the optical device 2, the fixing element 18, not illustrated, may be connected via the connecting element 17 to the protective cap 1, in particular its main body 16.

FIG. 7 illustrates another and optionally independent embodiment of the protective cap 1, the same reference numbers and component names being used for parts that are the same as those described in connection with FIGS. 1 to 6 above. To avoid unnecessary repetition, reference may be made to the detailed description given with reference to FIGS. 1 to 6 above.

The protective cap 1 illustrated here is also of a multi-layered design in the region of its end wall 3 and comprises the first layer 10, which is designed as a separate insert part 12. By contrast with the first layer 10 illustrated in FIGS. 1 to 3, this one is approximately cruciform or star-shaped in terms of its contour. The orifice 15 may be provided at the center 9 of the insert part 12, which provides a passage for the second layer 11.

The internal surface 14 of the protective cap 1 in this instance comprises the first layer 10 or insert part 12 made from it in certain regions on the one hand and the second or other layer 11. As viewed in the circumferential direction, individual arms 31 of the insert part 12 on its external circumference may be provided with the shoulders 13 described above, which may be accommodated or embedded in the cap casing 4.

The end wall 3 is therefore of a multi-layered design in some regions. At the center 9, the insert part 12 has the highest stiffness or strength in terms of the flexing needed for fitting on the optical device 2 as desired. In this respect, it should be pointed out that the selected shape of the insert part 12 based on a star or cross is just one of a plurality of other possible cross-sectional shapes.

FIGS. 8 and 9 illustrate another independent embodiment of the protective cap 1, the same reference numbers and component names being used for parts that are the same as those described in connection with FIGS. 1 to 7 above. To avoid unnecessary repetition, reference may be made to the detailed description of FIGS. 1 to 7 above.

In this instance, the protective cap 1 comprises only the main body 16 and it alone, made from the material of the second or other layer 11, and the arrangement comprising the first layer 10 or insert part 12 made from it is dispensed with.

In the region of its end wall 3, the protective cap 1 is formed by the material of the second layer 11, radially adjoined in the circumferential direction by the cap casing 4 and optionally the L-shaped retaining shoulder 5 with its legs 6, 7. The grip 19 as well as the fixing element 18 connected via the connecting element 17 to the protective cap 1 may also be provided. In order to retain clarity, the cut-outs 26, 27 and projection 28 have been omitted from the drawing. However, these components may naturally also be incorporated as described above.

To impart extra stiffness to the end wall 3 to prevent flexing or bending, at least one but preferably several web-type ribs 32 are provided on it. As viewed radially, the ribs 32 are disposed between the circumferentially extending cap casing 4 and thus impart the desired extra stiffness. If several such ribs 32 are provided on the internal surface 14 of the protective cap 1, in particular its end wall 3, they may extend out from the center 9 in a star shape or at an angle with respect to one another.

FIG. 10 illustrates another, optionally independent embodiment of the protective cap 1, the same reference numbers and component names being used for parts that are the same as those described in connection with FIGS. 1 to 9. To avoid unnecessary repetition, reference may be made to the detailed description of FIGS. 1 to 9 above.

The protective cap 1 illustrated here is of a multi-layered design at least in the region of its end wall 3 and comprises the first layer 10, the second layer 11 preferably joined to it, the cap casing 4 and optionally the L-shaped retaining shoulder 5 with its legs 6, 7.

In this respect, the first layer 10 is again a separate, independent, preferably flat and approximately disc-shaped component. Ribs 33 are provided on it on the side facing the optical device 2 and thus impart additional stiffness to the first layer 10. The insert part 12 therefore comprises the preferably disc-shaped first layer 10 and the ribs 33 molded onto it or integrally joined to it. The ribs 33 may be arranged in the same way as described above in connection with FIGS. 8 and 9 but in this instance are joined to the first layer 10.

In the external circumferential region of the insert part 12 or first layer 10, the preferably tubular shoulder 13 may be provided, which is accommodated by or embedded in the cap casing 4. To retain clarity and keep the drawing simple, the cut-outs 26, 27, projection 28 and fixing element connected via the connecting element 17 have been omitted from the drawing. These components may naturally also be used in this instance as described above.

The embodiments illustrated as examples represent possible variants of the protective cap 1, and it should be pointed out at this stage that the invention is not specifically limited to the variants specifically illustrated, and instead the individual variants may be used in different combinations with one another and these possible variations lie within the reach of the person skilled in this technical field given the disclosed technical teaching. Accordingly, all conceivable variants which can be obtained by combining individual details of the variants described and illustrated are possible and fall within the scope of the invention.

For the sake of good order, finally, it should be pointed out that, in order to provide a clearer understanding of the structure of the protective cap 1, it and its constituent parts are illustrated to a certain extent out of scale and/or on an enlarged scale and/or on a reduced scale.

The objective underlying the independent inventive solutions may be found in the description.

Above all, the individual embodiments of the subject matter illustrated in FIGS. 1 to 4; 5; 6; 7; 8, 9; 10 constitute independent solutions proposed by the invention in their own right. The objectives and associated solutions proposed by the invention may be found in the detailed descriptions of these drawings. 

1. Protective cap for a device, in particular a lens or ocular end of an optical device, such as an observation device, with an end wall and with a cap casing disposed around at least certain regions of the external circumference of the end wall, wherein the end wall comprises a first layer or a separate insert part formed therefrom in at least certain regions, and the material of the first layer or insert part has a higher modulus of elasticity than the material of the cap casing.
 2. Protective cap according to claim 1, wherein at least a partial portion of the end wall comprises several layers.
 3. Protective cap according to claim 2, wherein another one of the layers of the end wall is made from the same material as the cap casing.
 4. Protective cap according to claim 1, wherein a retaining shoulder which is L-shaped as viewed in axial section is disposed adjoining the cap casing, which in co-operation with its two legs and the cap casing bounds a preferably circumferentially extending housing compartment.
 5. Protective cap according to claim 1, wherein at least one projection is disposed on an external face of the cap casing projecting radially out from the cap casing.
 6. Protective cap according to claim 5, wherein the projection extends around the circumference of the cap casing.
 7. Protective cap according to claim 1, wherein at least one cut-out is disposed on the cap casing on its external face, which extends in the axial direction from an end face of the cap casing facing the end wall as far as the end wall.
 8. Protective cap according to claim 4, wherein at least one other cut-out is provided on an internal face of the leg of the retaining shoulder spaced at a distance radially outwards from the cap casing, which extends in the axial direction from a terminal end face of the leg as far as the first leg (6) of the retaining shoulder.
 9. Protective cap according to claim 1, wherein the first layer or insert part has a modulus of elasticity with a lower limit of 2000 MPa and an upper limit of 210000 MPa.
 10. Protective cap according to claim 1, wherein the first layer or insert part is made from a material selected from the group comprising plastic, metal, metal alloys, wood or a timber-like material, glass, ceramic.
 11. Protective cap according to claim 2, wherein the first layer or insert part is surrounded by the material used to form the second layer in at least certain regions, in particular is embedded in the second layer.
 12. Protective cap according to claim 2, wherein the first layer or insert part is joined to the material of the second layer in at least certain regions, in particular is injection molded or molded onto the second layer.
 13. Protective cap according to claim 1, wherein the first layer or insert part also has a tubular shoulder and the shoulder is embedded in the cap casing.
 14. Protective cap according to claim 1, wherein the first layer or insert part is cambered as viewed in axial section, starting from an external circumference to a center on the side facing the optical device to be protected, in particular is arcuately curved.
 15. Protective cap according to claim 1, wherein a rib is provided on the first layer or on the insert part on the side facing the optical device to be covered.
 16. Protective cap according to claim 2, wherein the first layer or insert part of the end wall is disposed on the side facing the optical device to be covered.
 17. Protective cap according to claim 2, wherein the first layer or insert part has at least one orifice at its center through which the material of the second layer extends.
 18. Protective cap according to claim 2, wherein the first layer or insert part of the end wall is disposed on the side facing away from the optical device to be covered.
 19. Protective cap according to claim 18, wherein the first layer or insert part has at least one projection which extends into the material of the second layer.
 20. Protective cap according to claim 19, wherein the projection is disposed at the center of the first layer or insert part.
 21. Protective cap according to claims 18, wherein the first layer or insert part is of a flat design and also has a flange in its external circumferential region projecting out from the tubular shoulder and the flange extends into the L-shaped retaining shoulder.
 22. Protective cap according to claim 18, wherein the material of the second layer is disposed in the region of an end face of the insert part or an end face of the flange facing away from the center disposed at a distance radially apart from it.
 23. Protective cap according to claim 2, wherein the second layer of the end wall, the cap casing and the retaining shoulder constitute a single cohesive main body and it is made from an elastomeric material such as silicone (synthetic polymers), in particular silicone 70 Shore A for example, or silicone caoutchouc or silicone rubber, rubber such as natural rubber or synthetic rubber, in particular nitrile rubber (NBR) or styrene-butadiene rubber (SBR), thermoplastic elastomers (TPE).
 24. Protective cap according to claim 2, wherein the second layer has a Shore hardness A with a lower limit of 50 and an upper limit of
 80. 